Basic QR Code Generator — Seaborn

A QR (Quick Response) code visualization that encodes text or URL data into a square matrix barcode pattern. QR codes are two-dimensional barcodes that store information in a grid of black and white squares, readable by smartphones and dedicated scanners. This visualization is useful for generating scannable codes for quick data sharing and mobile access.
Basic QR Code Generator rendered with Seaborn
Python source (Seaborn)

""" anyplot.ai
qrcode-basic: Basic QR Code Generator
Library: seaborn 0.13.2 | Python 3.13.14
Quality: 90/100 | Updated: 2026-06-24
"""

import os

import matplotlib.colors as mcolors
import matplotlib.pyplot as plt
import numpy as np
import qrcode
import seaborn as sns
from matplotlib.colors import ListedColormap


# Theme tokens — Imprint palette chrome
THEME = os.getenv("ANYPLOT_THEME", "light")
PAGE_BG = "#FAF8F1" if THEME == "light" else "#1A1A17"
ELEVATED_BG = "#FFFDF6" if THEME == "light" else "#242420"
INK = "#1A1A17" if THEME == "light" else "#F0EFE8"
INK_SOFT = "#4A4A44" if THEME == "light" else "#B8B7B0"
INK_MUTED = "#6B6A63" if THEME == "light" else "#A8A79F"
BRAND = "#009E73"  # Imprint palette position 1

# Configure seaborn with theme-adaptive background
sns.set_theme(
    style="white",
    rc={"figure.facecolor": PAGE_BG, "axes.facecolor": PAGE_BG, "axes.edgecolor": "none", "text.color": INK},
)

# WiFi credentials QR code (spec §Applications: "Generating WiFi network credentials")
# Version 7 (45×45 modules) showcases alignment patterns alongside the three finder patterns
encoded_content = "WIFI:S:AnyPlotLab;T:WPA2;P:OpenDataViz2024!;;"
qr = qrcode.QRCode(version=7, error_correction=qrcode.constants.ERROR_CORRECT_M, box_size=1, border=4)
qr.add_data(encoded_content)
qr.make(fit=False)

# Convert QR matrix to numpy array (includes 4-cell quiet zone on each side)
qr_matrix = np.array(qr.get_matrix(), dtype=np.uint8)
border = 4
n_modules = qr_matrix.shape[0] - 2 * border  # 45 for version 7

# QR colormap: 0=empty (elevated bg) → 1=filled module (ink) — theme-adaptive
qr_cmap = ListedColormap([ELEVATED_BG, INK])

# Square canvas: 2400×2400 px (figsize=(6,6) × dpi=400)
fig, ax = plt.subplots(figsize=(6, 6), dpi=400)
fig.set_facecolor(PAGE_BG)
ax.set_facecolor(PAGE_BG)

sns.heatmap(
    qr_matrix,
    ax=ax,
    cmap=qr_cmap,
    vmin=0,
    vmax=1,
    square=True,
    cbar=False,
    xticklabels=False,
    yticklabels=False,
    linewidths=0,
)

# Build region overlay matrix — NaN cells render transparent via seaborn heatmap (masked bad-color)
finder_size = 7
finder_positions = [
    (border, border),
    (border, qr_matrix.shape[1] - border - finder_size),
    (qr_matrix.shape[0] - border - finder_size, border),
]
align_module_centers = [(6, 22), (22, 6), (22, 22), (22, 38), (38, 22), (38, 38)]

region_matrix = np.full(qr_matrix.shape, np.nan)
for row, col in finder_positions:
    region_matrix[row : row + finder_size, col : col + finder_size] = 1.0
for am_row, am_col in align_module_centers:
    mr, mc = am_row + border, am_col + border
    region_matrix[mr - 2 : mr + 3, mc - 2 : mc + 3] = 2.0


# Second sns.heatmap overlays region colors using RGBA colors with built-in alpha so
# set_alpha() on the collection is not needed (it would override NaN transparency)
def _rgba(hex_color, alpha):
    r, g, b = mcolors.to_rgb(hex_color)
    return (r, g, b, alpha)


region_cmap = ListedColormap([_rgba(BRAND, 0.4), _rgba(INK_SOFT, 0.35)])
region_cmap.set_bad(alpha=0)  # NaN cells stay fully transparent
region_masked = np.ma.masked_invalid(region_matrix)
xlim, ylim = ax.get_xlim(), ax.get_ylim()
sns.heatmap(
    region_masked,
    ax=ax,
    cmap=region_cmap,
    vmin=0.5,
    vmax=2.5,
    cbar=False,
    xticklabels=False,
    yticklabels=False,
    linewidths=0,
)
ax.set_xlim(xlim)
ax.set_ylim(ylim)

# Remove all chrome for clean QR presentation
sns.despine(ax=ax, left=True, bottom=True, top=True, right=True)
ax.set_xlabel("")
ax.set_ylabel("")
ax.tick_params(left=False, bottom=False)

# Annotate the top-right finder pattern; label sits in the quiet zone area
fp_col = qr_matrix.shape[1] - border - finder_size
fp_row = border
fp_cx = fp_col + finder_size / 2
fp_cy = fp_row + finder_size / 2
ax.annotate(
    "Finder Pattern",
    xy=(fp_cx, fp_cy),
    xytext=(37, 1.8),
    fontsize=14,
    color=BRAND,
    ha="center",
    arrowprops={"arrowstyle": "->", "color": BRAND, "lw": 1.5},
)

# Annotate the center alignment pattern — label in bottom quiet zone
ap_mc = 22 + border
ap_mr = 22 + border
ax.annotate(
    "Alignment Pattern",
    xy=(ap_mc, ap_mr),
    xytext=(26, 51),
    fontsize=14,
    color=INK_SOFT,
    ha="center",
    va="center",
    arrowprops={"arrowstyle": "->", "color": INK_SOFT, "lw": 1.2},
)

# Quiet zone label — rotated text in the left quiet zone
ax.text(
    1.5,
    qr_matrix.shape[0] / 2,
    "Quiet Zone",
    fontsize=14,
    color=INK_MUTED,
    rotation=90,
    ha="center",
    va="center",
    fontstyle="italic",
)

# Title: mandatory format {spec-id} · {language} · {library} · anyplot.ai
title = "qrcode-basic · python · seaborn · anyplot.ai"
ax.set_title(title, fontsize=12, fontweight="bold", pad=10, color=INK)

# Subtitle with technical details
fig.text(
    0.5,
    0.025,
    f"WiFi: AnyPlotLab (WPA2)  ·  Error Correction: M (15%)  ·  Version {qr.version}  ·  {n_modules}×{n_modules} modules",
    ha="center",
    va="bottom",
    fontsize=10,
    color=INK_MUTED,
    fontstyle="italic",
)

plt.subplots_adjust(bottom=0.07, top=0.93, left=0.03, right=0.97)
plt.savefig(f"plot-{THEME}.png", dpi=400, facecolor=PAGE_BG)
Part of Basic QR Code Generator on anyplot.ai.
Basic QR Code Generator — Seaborn

Python source (Seaborn)

Other implementations
